That's also what all social media do , they put ads on your thoughts. They dont even need to index your thoughts because you submit them directly. It has nothing to do with being free, it's about incentives. Users are so foolish , they give everything for free, unlike webmasters.
You actually get to generate content for the platform for free.
Without you (all of the X users), the platform would be devoid of content, just botspeak and corporate promos.
Plus, as the sibling mentioned, they monetize your visit through ads (and data use).
It's just that they don't want to share the fractions of pennies with everyone, so the fractions accumulate for them.
Then they pay a bit to the higher tiers, so they create the illusion that X is a parallel income source, and gives the lower tiers something to aspire to.
Carrot and stick, or rather glass beads and the hope thereof.
Then maybe the recording companies will start defending artist rights.
Because not sure what all the other industry bodies are doing.
GPT-3 was trained on approximately 300 billion tokens. An small sized technical textbook might contain something like... 130,000 tokens? (1 token ~= 0.75 words, ~100k words in the book).
Thus, say you wrote a textbook on quantum mechanics that was included in the training corpus. A naive computation of the fraction of your textbook's contribution to the total number of training tokens would be 300B/130K = 0.0000004333333333, or 0.000043%.
If our hypothetical AI company here reported, say $500M in yearly profit, if all of that was distributed 100% based on our naive training token ratio (notice I say naive because it isn't as simple to say that every training token contributes equally to the final weights of a model. That is part of the magic.) then $500M * 0.000043% = $215.
You could imagine a simpler world where it was required by law that any such profitable company redistribute, say, %20 (taking the 'anti-VAT' idea) back to the copyright holders / originators of the training tokens. So, our fictitious QM textbook author would receive a check in the mail for $43 for that year of $500M in revenue. Not great, but not zero.
Since then, training corpuses are much, much larger, and most people's contributions would be much smaller. Someone who writes witty tweets? Maybe 1/100th the length of our above example in am model with now 100x the training corpus.
So fractions of a penny for your tweets. Maybe that is fitting after all...